Diaphragm carburetor

ABSTRACT

Disclosed herein is a carburetor which includes two diaphragm chambers within the carburetor housing. One diaphragm chamber forms part of a pulse actuated fuel pump and the other diaphragm chamber is the main fuel metering diaphragm chamber. Both the fuel pump and the main diaphragm chamber are formed from opposed recesses in mating surfaces of a housing cover and a housing surface. The opposed recesses forming each diaphragm chamber are separated by a common diaphragm which extends between the mating surfaces of the cover and housing. The fuel pump is operated by pressure variations in the crankcase which communicate with the fuel pump through a passage in the carburetor housing.

United States Patent [19] Du Bois [451 Oct. 16, 1973 DIAPHRAGMCARBURETOR Inventor; Chester Dufioiizioml llj Assignee: Outboard MarineCdrptiratiiin,

Waukegan, Ill.

[22] Filed: Oct. 25, 1968 [21] Appl. No.: 770,645

[52] US. Cl 261/37, 261/40, 261/71,

261/DIG. 68 [51] Int. Cl. B0ld 47/00 [58] Field of Search 261/34, 35,37, 69.1,

261/24, DIG. 68, 40, 71; 103/40, 150; 123/1398 Primary ExaminerDennis E.Talbert, Jr. Attorney-Robert K. Gerling and Clemency, Michaels, Foster,Michaels, Puerner, Gemignanis and Riteris [5 7] ABSTRACT Disclosedherein is a carburetor which includes two diaphragm chambers within thecarburetor housing. One diaphragm chamber forms part of a pulse actuatedfuel pump and the other diaphragm chamber is the main fuel meteringdiaphragm chamber. Both the fuel pump and the main diaphragm chamber areformed from opposed recesses in mating surfaces of a housing cover and ahousing surface. The opposed recesses forming each diaphragm chamber areseparated by a common diaphragm which extends between the matingsurfaces of the cover and housing. The fuel pump is operated by pressurevariations in the crankcase which communicate with the fuel pump througha passage in the carburetor housing.

5 Claims, 14 Drawing Figures Patented Oct. 16, 1973 2 Sheets-Sheet 1 M r%M /70{ ArL/( h vNvENT'oR CHESTER 0050/5 BY M, m, bud-FM ATTO RNEY SBACKGROUND OF INVENTION In some prior carburetors a separate fuel pumpis typically used to supply fuel to the fuel chamber portion of adiaphragm chamber. When the fuel pump is integral with the carburetorhousing the main diaphragm chamber and fuel pump chamber are typicallyin a stacked array with the two chambers separated by an intermediatehousing partition. This construction requires the use of several gasketsand close tolerances to insure alignment of connecting passages andresults in high assembly time and manufacturing costs.

SUMMARY OF INVENTION The invention provides a diaphragm carburetor whichutilizes a common diaphragm for the main metering diaphragm chamber anda pulse actuated fuel pump or second diaphragm chamber located withinthe same carburetor housing. The use of a common diaphragm is madepossible by a construction in which the two diaphragm chambers arelocated along the interface or mating surfaces of the housing and ahousing cover. The common diaphragm separates two sets of opposedrecesses in the cover and housing into fuel chamber portions and airchamber portions for both diaphragm chambers. The air chamber portion ofthe fuel pump communicates with the engine crankcase through a passagein the carburetor housing. Pressure variations from the crankcase causea fluctuation of the diaphragm in the fuel pump to induce flow through afuel conduit into the fuel chamber portion of the fuel pump and from thefuel pump to the main diaphragm chamber.

A flapper type check valve formed from the common diaphragm is providedfor the main orifice to prevent back bleeding of air into the idlesystem when the engine is idling. The flapper type check valveeliminates the need for a special valve seat and housing assembly forthe valve components, thus decreasing the cost of manufacture.

Further objects and advantages of the invention will become apparentfrom the following disclosure.

DRAWINGS FIG. 1 is a fragmentary sectional view of a two cycle engineembodying the carburetor of the invention.

FIG. 2 is a schematic view of a carburetor in accordance with theinvention.

FIG. 3 is an enlarged top view of the carburetor shown in FIG. 1 and afragmentary view of the engine.

FIG. 4 is a sectional view taken along line 44 of FIG. 3.

FIG. 5 is a top view of the carburetor housing with the cover removed.

FIG. 6 is a sectional view taken along line 6--6 of FIG. 5.

FIG. 7 is a sectional view taken along line 77 of FIG. 5.

FIG. 8 is a plan view of the diaphragm shown in FIGS. 3, 4, 5 and 6.

FIG. 9 is a sectional view taken along line 99 of FIG. 5.

FIG. 10 is a sectional view taken along line 10-10 of FIG. 5.

FIG. 11 is a sectional view taken along line II-ll of FIG. 5.

FIG. 12 is an enlarged sectional view taken along line 12-12 of FIG. 13.

FIG. 13 is a plan view of the valve member shown in FIG. 12.

FIG. 14 is an enlarged sectional view taken along line 14-14 of FIG. 5.

' DETAILED DESCRIPTION Referring to FIG. 1, there is shown a two cycleengine 106 having a crankcase 108 with a crankcase reed valve 110located in a crankcase induction passage 112. A carburetor 114 isconnected to the engine 106. As shown in the schematic diagram in FIG.2, the carburetor 114 has a body 115 which includes a housing 118 and ahousing cover 1 17. The housing 118 includes a fuel-air inductionpassage 1 16. The induction passage 1 16 communicates with the crankcasethrough the passage 112 and the reed valve 110. The carburetor alsoincludes a venturi 120, a mixing chamber 122 which communicates with ahigh speed jet or fuel inlet 124, and a throttle shutter 126.

In accordance with the invention, means are provided defining a first ormain metering diaphragm chamber 128 and a fuel pump or second diaphragmchamber 130 in the carburetor body 115. In the construction disclosed inFIG. 2, the first diaphragm chamber 128 is defined by a recess orrelieved wall portion 132 in housing 118 and a complementary opposedrecess or relieved wall portion 134 in the housing cover 117. The seconddiaphragm chamber 130 is defined by a relieved wall portion 138 in upperface 140 of housing 118 and a complementary opposed relieved wallportion 142 in the cover 117.

The location of the first and second diaphragm chambers 128 and 130along the interface between the cover 117 and the adjacent housingsurface affords the use of a single diaphragm 148 for both diaphragmchambers 128 and 130. The first diaphragm chamber 128 is separated intoa fuel chamber portion 144 and an air chamber portion 146 by thediaphragm 148 which can extend the full length and width of the housingface or surface 140 and which has a diaphragm section 149 locatedbetween recesses 132 and 134. Air chamber portion 146 communicates withthe atmosphere through a vent or passage 154.

The diaphragm 148 also has a section 151 which separates diaphragmchamber 130 into a fuel chamber portion and an air chamber portion 152.The air chamber portion of the second diaphragm chamber 130 communicateswith the crankcase 108 through a passage 156 which communicates pressurepulses or variations in the crankcase 108 to the air chamber portion152, thus causing fluctuations of the diaphragm section 151 in thesecond diaphragm chamber 130 to pump fuel to the first diaphragm chamberas hereinafter described.

Fuel is supplied to the fuel chamber portion 150 through a fuel passage160 which extends through housing 118 and which has a nipple 162exteriorly of the housing 118 for connection to the fuel supply (notshown).

To minimize construction costs and eliminate conventional check valvesrequiring a valve seat and check member, the passage 160 is providedwith a flap valve 164 which is formed from the diaphragm 148 by removalof an arcuate portion of the diaphragm by stamping or cutting, leaving aflap 164 in the form of a flexible tongue which is hinged along one edgeto the diaphragm 148. The flap 164 is movable into a valve chamber 166which communicates with the fuel chamber portion 150 of the seconddiaphragm chamber 130 by a passage 168. Valve 164 permits fluid flowinto the fuel chamber portion but prevents fuel outflow from the fuelchamber portion 150 through conduit or passage 160, thus causing apumping action to supply fuel to the first diaphragm chamber 128.

Fuel flow from the fuel chamber portion 150 to the fuel chamber portion144 of the first diaphragm chamber 128 is provided by a passage 170. Thepassage 170 and the fuel chamber portion 150 are provided with an outletvalve in the form of a flap 172 which extends over an opening 174 whichcommunicates with the fuel chamber portion 150. The flap valve 172 ismovable in a valve chamber 176 which communicates with the passage 170.

In the alternative the valve 172 can be located at the interface betweenthe cover 117 and the housing 118 and and formed from a portion of thediaphragm 148.

Fuel is emitted or metered into the fuel chamber portion 144 of the maindiaphragm chamber by a valve member 179 which is located in a bore orvalve chamber 180 in the housing 118 and which communicates with thefuel chamber portion 144. Valve member 179 is actuated by an arm 181which is pivoted to the housing at 182 and spring biased into engagementwith a button 183 on the diaphragm 148 by a spring 184 located in thefuel chamber portion 144. Fuel is supplied to the high speed nozzle orfuel outlet 124 by a passage 185 controlled by a metering valve 186.Fuel flow into the passage 185 is controlled by a flap valve 187 formedfrom a portion of diaphragm 148 which closes across the end ofa passage188 in housing 118. Passage 188 communicates with the fuel chamberportion 144 at 189.

Idle fuel is supplied to idling orifices 190 through a passage 192 whichis located in the housing 118 and which is controlled by an idlemetering valve 193.

A preferred embodiment of the invention is disclosed in FIG. 1 and FIGS.3 through 13. As shown in FIGS. 4, 9 and 10, a carburetor 214 has a body215 which includes a housing 218 and a housing cover 217. The housing218 includes a fuel-air induction passage 216. The carburetor inductionpassage 216 has a venturi 220 (FIG. 4) and a mixing chamber 222 whichcommunicates with a high speed jet or fuel inlet 224. A throttle shutter226 regulates flow to the engine crankcase.

In the preferred embodiment, the means defining a first diaphragmchamber 228 in the housing 218 comprises a recess or relieved wallportion 232 (FIGS. 4, 11) in the housing 218 and a complementary opposedrecess or relieved wall portion 234 in the housingvcover 217 which isbolted or otherwise secured to the housing 218. The means defining asecond diaphragm chamber 230 comprises a recess or relieved wall portion238 (FIGS. 7, 11) in the upper face 240 of the housing 218 and acomplementary recess or opposed relieved wall portion 242 in the cover217.

The diaphragm chamber 228 is separated into a fuel chamber portion 244and an air chamber portion 246 by a diaphragm 248 which extends the fulllength and width of face 240 and is sandwiched between the cover 217 andthe housing 218. Diaphragm 248 has a diaphragm section 249 locatedbetween the recesses 232 and 234. The diaphragm 248 has a section 251which separates the second diaphragm chamber 230 into a fuel chamberportion 250 and an air chamber portion 252. The air chamber portion 246communicates with the atmosphere through a vent passage 254 (FIG. 1 l).The air chamber portion 252 of the second diaphragm chamber 230communicates with the engine crankcase 108 through a passage 256 (FIGS.3 and 5).

Fuel is supplied to the fuel chamber portion 250 of the second diaphragmchamber 230 by a fuel passage 260 (FIG. 7) which extends through aportion of housing 218 and has a nipple 262 adapted to be connected to afuel line or to the fuel supply.

Passage 260 is provided with a fuel inlet valve 264 (FIGS. 5, 7) whichcomprises a flap 265 which is formed by cutting or stamping thediaphragm to remove a portion of the diaphragm, as shown in FIG. 8. Theflap is movable within a valve chamber 266 (FIG. 7) to permit fuelinflow and prevent fuel outflow during pumping action of the diaphragmsection 251 located within the diaphragm chamber 230.

Fuel is conveyed from the fuel chamber portion 250 to the fuel chamberportion 244 of the first diaphragm chamber 228 by a passage 270 (FIGS.3, 6, 12). Fuel flow into the passage 270 is controlled by an outletcheck valve 271 (FIGS. 12, 13) in the form of a flap 272 which extendsover an aperture 274 which communicates with the fuel chamber portion250. The flap 272 is movable between a support 273 and a downwardlyextending boss 275 on the cover 217.

Fuel is metered into the fuel chamber portion 244 by a valve member 279(FIGS. 6, 11) located in a bore or valve chamber 280 in the housing 218.The valve member 279 is actuated by an arm 281 which is pivoted to thehousing at 282 and is spring biased into engagement with a button 283 ondiaphragm 248 by a spring 284 located in the fuel chamber portion 244.Fuel flow from the fuel chamber portion 244 into the mixing chamber 222through the outlet 224 is provided by a passage 285 (FIG. 9) controlledby a flap check valve 287 (FIGS. 8, 14). The metering valve 286 providescarburetor adjustment.

Idle fuel is supplied to idling orifices 290 (FIGS. 4, 10) through apassage 292 which communicates with the fuel chamber portion 232 and iscontrolled by a valve 293 (FIG. 10).

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:

1. A carburetor comprising a carburetor body including a housing with aface having therein a fuel recess and a recess for gas under pulsatingpressure, said housing also including an air induction passage providedwith a fuel inlet, a first passage communicating between said fuel inletand said fuel recess, a second passage communicating between said fuelrecess and said face, a third passage communicating with said face andadapted to communicate with a source of fuel, and a fourth passagecommunicating with said recess for gas under pulsating pressure andadapted to communicate with a source of pulsating pressure gas, a singleflexible diaphragm engaged with said housing face and having a firstportion extending across said fuel recess, and a second portionextending across said recess for gas under pulsating pressure, a housingcover with a face having therein an air-chamber recess, and a fuelpumping recess adapted to communicate with a source of fuel, saidhousing cover also including a first passage communicating with saidcover face and with said fuel pumping recess and a second passagecommunicating between said fuel pumping recess and said cover face, andmeans detachably connecting said cover to said housing with said fuelrecess and said air-chamber recess in opposing relation to each otherwith said first diaphragm portion therebetween, with said recess for gasunder pulsating pressure and said fuel pumping recess in opposingrelation to each other with said second diaphragm portion therebetween,with said second passage in said housing communicating with said firstpassage in said cover and with said second passage in said covercommunicating with said third passage in said housing.

2. A carburetor comprising a carburetor body including a housing with aface having therein a fuel recess and a recess for gas under pulsatingpressure, said housing also including an air induction passage providedwith a fuel inlet, a first passage communicating between said fuel inletand said fuel recess, a second passage communicating between said fuelrecess and said face, and a third passage communicating with said faceand adapted to communicate with a source of fuel, a single flexiblediaphragm engaged with said housing face and having a first portionextending across said fuel recess, a second portion extending acrosssaid recess for gas under pulsating pressure, and a third portionextending across the end of said third house passage at said face andincluding fapper valve means for permitting flow from and preventingflow to said third housing passage, a housing cover with a face havingtherein an air-chamber recess, and a fuel pumping recess adapted tocommunicate with a source of fuel, said housing cover also including afirst passage communicating with said cover face and with said fuelpumping recess and a second passage communicating between said fuelpumping recess and said cover face, and means detachably connecting saidcover to said housing with said fuel recess and said air-chamber recessin opposing relation to each other with said first diaphragm portiontherebetween, with said recess for gas under pulsating pressure and saidfuel pumping recess in opposing relation to each other with said seconddiaphragm portion therebetween, with said second passage in said housingcommunicating with said first passage in said cover, and with saidsecond passage in said cover communicating with said third passage insaid housing subject to the control of said flapper valve means.

3. A carburetor comprising a carburetor body including a housing with aface having therein a fuel recess and a recess for gas under pulsatingpressure, said housing also including an air induction passage providedwith a high speed fuel inlet, a first passage communicating between saidhigh speed fuel inlet and said face, a

second passage communicating between said fuel recess and said face, afuel supply passage communicating between said fuel recess and saidface, and a fourth passage communicating with said face and adapted tocommunicate with a source of fuel, a single flexible diaphragm engagedwith said housing face and having a first portion extending across saidfuel recess, a second portion extending across said recess for gas underpulsating pressure, a third portion extending across the end of saidsecond housing passage at said face and including a flapper valve meansadapted for permitting flow from and preventing flow to said secondhousing passage, and a fourth portion extending across the end of saidfourth housing passage at said face and including second flapper valvemeans for permitting flow from and preventing flow to said fourthhousing passage, a housing cover with a face having therein anairchamber recess and a fuel pumping recess, said housing cover alsoincluding a first fuel passage communicating with said cover face, asecond fuel passage communicating with said cover face and with saidfuel pumping recess, and a third passage communicating between said fuelpumping recess and said cover face, means detachably connecting saidcover to said housing with said fuel recess and said air-chamber recessin opposing relation to each other with said first diaphragm portiontherebetween, with said recess for gas under pulsating pressure and saidfuel pumping recess in opposing relation to each other with said seconddiaphragm portion therebetween, with said first passage of said covercommunicating with said first and second passages of said housingsubject to the control of said first flapper valve means, with said fuelsupply passage in said housing communicating with said second passage insaid cover and with said third passage in said cover communicating withsaid fourth passage in said housing subject to the control of saidsecond flapper valve means, whereby said cover can be removed to affordaccess to said diaphragm without other disconnection.

4. A carburetor in accordance with claim 3 wherein said housing includesan idle fuel inlet, a fifth passage communicating between said fuelrecess and said idle fuel inlet, and a sixth passage communicating withsaid recess for gas under pulsating pressure and adapted to communicatewith a source of pulsating pressure.

5. A carburetor in accordance with claim 4 wherein said housing coveralso includes an air vent extending through said cover and communicatingwith said airchamber recess, and wherein said fuel pumping recessincludes a recessed portion, and further including a flapper valvelocated in said recessed portion for permitting fuel flow from andpreventing flow to said fuel pumping recess, and wherein said secondfuel passage in said cover communicates with said face and with saidrecessed portion of said fuel pumping recess subject to the control ofsaid flapper valve.

1. A carburetor comprising a carburetor body including a housing with aface having therein a fuel recess and a recess for gas under pulsatingpressure, said housing also including an air induction passage providedwith a fuel inlet, a first passage communicating between said fuel inletand said fuel recess, a second passage communicating between said fuelrecess and said face, a third passage communicating with said face andadapted to communicate with a source of fuel, and a fourth passagecommunicating with said recess for gas under pulsating pressure andadapted to communicate with a source of pulsating pressure gas, a singleflexible diaphragm engaged with said housing face and having a firstportion extending across said fuel recess, and a second portionextending across said recess for gas under pulsating pressure, a housingcover with a face having therein an air-chamber recess, and a fuelpumping recess adapted to communicate with a source of fuel, saidhousing cover also including a first passage communicating with saidcover face and with said fuel pumping recess and a second passagecommunicating between said fuel pumping recess and said cover face, andmeans detachably connecting said cover to said housing with said fuelrecess and said air-chamber recess in opposing relation to each otherwith said first diaphragm portion therebetween, with said recess for gasunder pulsating pressure and said fuel pumping recess in opposingrelation to each other with said second diaphragm portion therebetween,with said second passage in said housing communicating with said firstpassage in said cover and with said second passage in said covercommunicating with said third passage in said housing.
 2. A carburetorcomprising a carburetor body including a housing with a face havingtherein a fuel recess and a recess for gas under pulsating pressure,said housing also including an air induction passage provided with afuel inlet, a first passage communicating between said fuel inlet andsaid fuel recess, a second passage communicating between said fuelrecess and said face, and a third passage communicating with said faceand adapted to communicate with a source of fuel, a single flexiblediaphragm engaged with said housing face and having a first portionextending across said fuel recess, a second portion extending acrosssaid recess for gas under pulsating pressure, and a third portionextending across the end of said third house passage at said face andincluding fapper valve means for permitting flow from and preventingflow to said third housing passage, a housing cover with a face havingtherein an air-chamber recess, and a fuel pumping recess adapted tocommunicate with a source of fuel, said housing cover also including afirst passage communicating with said cover face and with said fuelpumping recess and a second passage commuNicating between said fuelpumping recess and said cover face, and means detachably connecting saidcover to said housing with said fuel recess and said air-chamber recessin opposing relation to each other with said first diaphragm portiontherebetween, with said recess for gas under pulsating pressure and saidfuel pumping recess in opposing relation to each other with said seconddiaphragm portion therebetween, with said second passage in said housingcommunicating with said first passage in said cover, and with saidsecond passage in said cover communicating with said third passage insaid housing subject to the control of said flapper valve means.
 3. Acarburetor comprising a carburetor body including a housing with a facehaving therein a fuel recess and a recess for gas under pulsatingpressure, said housing also including an air induction passage providedwith a high speed fuel inlet, a first passage communicating between saidhigh speed fuel inlet and said face, a second passage communicatingbetween said fuel recess and said face, a fuel supply passagecommunicating between said fuel recess and said face, and a fourthpassage communicating with said face and adapted to communicate with asource of fuel, a single flexible diaphragm engaged with said housingface and having a first portion extending across said fuel recess, asecond portion extending across said recess for gas under pulsatingpressure, a third portion extending across the end of said secondhousing passage at said face and including a flapper valve means adaptedfor permitting flow from and preventing flow to said second housingpassage, and a fourth portion extending across the end of said fourthhousing passage at said face and including second flapper valve meansfor permitting flow from and preventing flow to said fourth housingpassage, a housing cover with a face having therein an air-chamberrecess and a fuel pumping recess, said housing cover also including afirst fuel passage communicating with said cover face, a second fuelpassage communicating with said cover face and with said fuel pumpingrecess, and a third passage communicating between said fuel pumpingrecess and said cover face, means detachably connecting said cover tosaid housing with said fuel recess and said air-chamber recess inopposing relation to each other with said first diaphragm portiontherebetween, with said recess for gas under pulsating pressure and saidfuel pumping recess in opposing relation to each other with said seconddiaphragm portion therebetween, with said first passage of said covercommunicating with said first and second passages of said housingsubject to the control of said first flapper valve means, with said fuelsupply passage in said housing communicating with said second passage insaid cover and with said third passage in said cover communicating withsaid fourth passage in said housing subject to the control of saidsecond flapper valve means, whereby said cover can be removed to affordaccess to said diaphragm without other disconnection.
 4. A carburetor inaccordance with claim 3 wherein said housing includes an idle fuelinlet, a fifth passage communicating between said fuel recess and saididle fuel inlet, and a sixth passage communicating with said recess forgas under pulsating pressure and adapted to communicate with a source ofpulsating pressure.
 5. A carburetor in accordance with claim 4 whereinsaid housing cover also includes an air vent extending through saidcover and communicating with said air-chamber recess, and wherein saidfuel pumping recess includes a recessed portion, and further including aflapper valve located in said recessed portion for permitting fuel flowfrom and preventing flow to said fuel pumping recess, and wherein saidsecond fuel passage in said cover communicates with said face and withsaid recessed portion of said fuel pumping recess subject to the controlof said flapper valve.